Visualization of the law of cosines
c
2
= a
2
+ b
2
- 2ab cos θ
When θ=180, the law of cosines is (a+b)
2
= a
2
+ b
2
+ 2ab.
When θ=90, the law of cosines is the Pythagorean theorem.
Gif © 2018
Linda Brown Westrick